Drilling system with plural below ground motors



Dec. 15, 1964 F. F. DAVIS 3,161,243

DRILLING SYSTEM WITH PLURAL BELOW GROUND MOTORS Filed July 22, 1960 ll Sheets-Sheet 1 E'VEEE #18 JNVENTOR. FRflNKE DA v/s ATTORNEYJ Dec. 15, 1964 F. F. DAVIS 3,161,243

DRILLING SYSTEM WITH PLURAL BELOW GROUND MOTORS Filed July 22. 1960 11 Sheets-Sheet 2 FIG.3

Ali ,8 W

INVENTOR.

FRANK E 0/: W6

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15, 1964 F. F. DAVIS 3,161,243

DRILLING SYSTEM WITH PLURAL BELOW GROUND MOTORS Filed July 22, 1960 l1 Sheets-Sheet 3 FIG. 5 W I i g M ATTORNEYS Dec. 15, 1964 F. F. DAVIS 3,161,243

DRILLING SYSTEM WITH PLURAL BELOW GROUND MOTORS Filed July 22, 1960 11 Sheets-Sheet 4 IN VEN TOR. FRANKEDA v/s ATTORNEYS Dec. 15, 1964 F. F. DAVIS 3,161,243

DRILLING SYSTEM WITH PLURAL BELOW GROUND MOTORS Filed July 22, 1960 11 Sheets-Sheet 5 7 FIG-.9

. IN V EN TOR. FRANK EDA V/J' ATTORNEYS Dec. 15, 1964 F. F. DAVIS 3,161,243

DRILLING SYSTEM WITH PLURAL BELOW GROUND MOTORS Filed July 22, 1960 ll Sheets-Sheet e FIST/2 7 1 F16. IO

IN V EN TOR. FRANKE DAV/6 AI'TORNEYJ F. F. DAVIS Dec. 15, 1964 DRILLING SYSTEM WITH PLURAL. BELOW GROUND MOTORS ll Sheets-Sheet 7 Filed July 22, 1960 INVENTOR. FRANK EDA V16 BY \-M ATTORNEYJ Dec. 15, 1964 F. F. DAVIS 3,161,243

DRILLING SYSTEM WITH PLURAL. BELOW GROUND MOTORS Filed July 22, 1960 11 Sheets-Sheet 8 IN VEN TOR. FRA/vKEDAws ATTORNEYJ Dec. 15, 1964 F. F. DAVIS 3,161,243

DRILLING SYSTEM WITH PLURAL BELOW GROUND MOTORS Filed July 22, 1960 11 Sheets-Sheet 9 IN V EN TOR. FRANKE DAV/6' Dec. 15, 1964 F. F. DAVIS 3,161,243

DRILLING SYSTEM WITH PLURAL. BELOW GROUND MOTORS Filed July 22, 1960 11 Sheets-Sheet 10 FIG. [8

IN VEN TOR. FRANK E DA V16 wwww ATTORNEYJ Dec. 15, 1964 F. F. DAVIS 3,161,243

DRILLING SYSTEM WITH PLURAL BELOW GROUND MOTORS Filed July 22, 1960 11 Sheets-Sheet l1 IN VEN TOR. FRANK Ff DA v/s ATTORNEYS United States Patent Office 3,161,243 DRILLING SYTEM WITH PLURAL BELOW GROUND MGTORS Frank F. Davis, Sacramento, Caiif. (1029 2nd St, Santa Monica, Calif.) Filed July 22, 196i), Ser. No. 44,673 17 (Ilairns. (Cl. 175-95) This invention relates to a complete drilling system for boring large diameter holes in the surface of the earth. More particularly, this invention relates to a rotary drilling system for sinking large diameter holes of circular cross section and about five to fifteen foot diameter for mine shafts, ventilation,emergency escapeways, and the like. The drilling system of this invention is adapted to the boring of large diameter holes up to five hundred feet in depth or more depending upon acual conditions encountered at the site.

Because an almost limitless variety of conditions is to be expected at various shaft locations and even at various depths in a single shaft, the drilling system is versatile and adapted to use in many variations dependent upon actual conditions. Conditions which effect drilling include hardness of rock, strength of rock, the nature of rock defects (including their prominence, orientaton, regularity, and frequency), rock porosity and permeability, the amounts and pressures of rock fluids (generally water, but on rare occasions, oil or gas or mixtures or solutions of them).

According to the present invention, the drill stem (drill column or drill pipe) does not rotate about its long axis but serves as a conductor for the passage for one or more fluids into or out of the hole, a means of resisting torque originating in rotating elements at the bottom of the hole, a means of raising or lowering the rotating elements, a means of applying pressure to the rotating elements and a guide or slide on which a cuttings carrier may travel up and down in the hole.

The rotating elements at the bottom of the hole at the end of the stationary drill stem includes a plurality of any one of a number of conventional cutting members. These cutting members may be rolling cutters such as usually used in oil well bits, diamond set saws, drags bits, rolling discs and the like. The cutting members are held in mill housings for rotation over the full shaft bottom. The rotary elements are driven from power means contained within the mill housing at the bottom of the hole.

The principal object of this invention is to provide a complete drilling system and equipment for boring shafts of circular cross section and large diameter in the surface of the earth.

A further object of this invention is to provide a drilling system for boring large diameter holes in the earths surface utilizing a stationary drill stem and rotary cutting elements driven from power means at the end of the drill stem at the bottom of the hole.

A still further object of this invention is to provide a versatile drilling system adapted to the drilling of large dameter holes under widely varying natural conditions.

Still another object of this invention is to provide a drilling system including a novel and versatile cuttings carrier adapted to the performance of a variety of functions.

Other objects of the invention will become apparent as the description proceeds.

To the accomplishment of the foregoing and relating ends, this invention then comprises the features hereinafter fully described and particularly pointed out in the claims, the following description setting forth in detail certain illustrative embodiments of the invention, these being indicative, however, of but a few of the various ways in which the principles of the invention may be employed.

The invention is illustrated by the drawings in which the same numerals refer to corresponding parts and in which:

FIGURE 1 is a simplified schematic representation of the elements comprising the drilling system of the present invention, including both the surface and down-hole components;

FIGURE 2 is a plan of the derrick floor and auxiliary components;

FIGURE 3 is an elevation of derrick structure which may be employed as part of the drilling system;

FIGURE 4 is a plan view of a portion of the derrick and derrick floor structure showing torque resisting means for holding the drilling stems stationary;

FIGURE 5 is a partial elevation showing the torque resisting means;

FIGURE 6 is a partial plan of the derrick floor showing spider means for suspending the drill stem when adding or removing drill stem sections;

FIGURE 7 is a fragmentary section through the spider means on the line 7--7 of FIGURE 6 and in the direction of the arrows;

FIGURE 8 is a horizontal section through a drill stem element taken generally on the line 88 of FIGURE 9 and in the direction of the arrows;

FIGURE 9 is a vertical section through the ends of two adjacent drill stem elements taken on the line 99 of FIGURE 8 and in the direction of the arrows;

FIGURE 10 is a top plan view of the cuttings carrier comprising part of the present drilling system;

FIGURE 11 is a fragmentary vertical section through the cuttings carrier in place in a bore hole;

FIGURE 12 isa fragmentary horizontal section taken on the line 12-12 of FIGURE 11 and in the direction of the arrows;

FIGURE 13 is a fragmentary vertical section through the cuttings carrier in place in a bore hole and equipped for use as a swab;

FIGURE 14 is a fragmentary horizontal section taken on the line 14-44 of FIGURE 13 and in the direction of the arrows;

FIGURE 15 is a vertical section through one form of a rotary drill mill shown in working position at the bottom of a bore hole;

FIGURE 16 is a bottom view of the drill mill showing the drill mill cutting elements in working position;

FIGURE 17 is a bottom view similar toFIGURE 16 but showing the drill mill cutting elements retracted for movement of the drill mill into or out of the bore hole;

FIGURE 18 is a vertical section through a modified form of drill mill; and

FIGURE 19 is a bottom View of the modified drill mill utilizing diamond set saws.

Referring to the drawings and particularly to FIG- URES 1 and 2, there is shown in simplified and schematic form, the overall arrangement of components comprising the large bore hole drilling system of the present invention. These components include a derrick structure, indicated generally at 10 and rising vertically above the bore hole in the earth's surface, indicated generally at 11. The top platform (or Water table) of the derrick is fitted in the conventional manner with a plurality of sheaves 12 adapted to receive cables or lines 13 which in turn extend to power driven winches 14 or similar power driven draw works. The derrick and associated mechanism is supported from a deck or floor 15 supported slightly above the earths surface. A pipe rack 16 for holding drill stem sections is placed conveniently nearby. One or more block and tackle arrangements 17 are provided within the derrick structure for pulling sections of the drill stern, indicated generally at 18, and performing other hoisting functions.

A mud pit 19 is provided to contain drilling mud or Patented Dec. 15, 1964..

anemia other drilling fluid which is pumped through one or more mud pumps 20 through hose 21 to the drill stem and to the bottom of'the bore hole for lubrication of the cutting elements and to assist in removal of cuttings from.

the bore hole. A swinging spout 22 is provided at the surface to receive mud and cuttings from the cuttings carrier in a manner to be explained in greater detail hereinafter and convey them to a screen 23 from which the drill mud returns through a flume or conduit to the mud.

suspending the 'drill stem while adding or removing drill stem sections. A cuttings carrier, indicated generally at 27 (and shown in greater detail in FIGURES through 14), surrounds the drill stem at a point between the, surface and the bottom of the bore hole. Adrill mill, indicated generally at 28 (and shown in greater detail in FIGURES through 19), performs the cutting operation at the bottom of the bore hole. additional pressure is desired to be exerted against the drill mill, added weight may be applied at thetop of the drill. mill at '29 for this purpose.

if necessary.

Surface Components A shelter of some sort is desirably 1 Where Wall jacks 30 may optionally be provided for alignment of the drill mill,

. 4 the two jaws 46 are brought together on opposite side of the drill stem and the facing flanges 47 of the opposite jaw members are secured together as by means of bolts 48 and nuts 49 With the jaws thus gripping the drill stem, the stem is held against rotation. The facing flanges of the opposite jaws are not secured together so tightly, however, as to inhibit vertical movement of the drill stem. Thus, the drill stem may pass progressively through the gripping jaws at the same rate as the drill mill at the bottom end of the drill stem-cuts its way deeper into the earth. A plurality of clevis-like. devices 40 are preferably provided at different heights along the derrick to permit the drill stem to be held against rotation at that height above the derrick floor which is most convenient to the operator under particular operating conditions. When the drill mill is not operating and it is desired to raise or lower the drill stem to add or remove drill stem sections, the jaws are simply unbolted and swung out ofvthe way Then when drilling operations are swung back into position on their pivoted arms. resumed, the jawsiand arms are and secured together.

In FIGURES 6 and 7, there is shown a spider means for suspending the drill stem in the bore hole while adding'and removing drill stern sections. It will be readily understood to those skilled in the art that as drilling proceeds, additional drill stem sections must be added to lengthen the drill stem as the drill mill cuts its way deeper [into the earth. Each time the drill mill has progressed Referring now to FIGURES 3 through 7, certainjof the surface components are shown in greater detail. Derrick structure is shown in-greater detail in'FIGURE 3. The water table or sheave deck 31 at the top of the derrick is adapted to mount a plurality of sheaves of which sheaves 12A, 12B and 120 are shown. The plurality of winches or hoists 14A, 14B and 14C along with the plurality of sheavesand suitable lines or cables 13A, l '3B and 130 can be made to perform a large variety of different jobs. In the arrangement as shown, hoist 14B functions as a drill stem hoist by means of cable 133, sheave 12B, and tackle device 173. 'Cables 13A and 13C and sheaves 12A and 12C operate floor tackle elements 17A and 170, respectively, for hoisting of drill stem sections, the cuttings carrier, derrick floor sections and the like.

A manifold 32 is suspended from drill stem tackle 17B. Manifold32 is-provided with a plurality of connections 33-36 for introducing mud, water, air, oil, electric power lines, and the like to separate :channels of the drill stem and the drill mill and for the return of one or more of these mateials as required by the particular.

drilling arrangement used. Manifold '32'isprovided with a flanged face plate 37 corresponding to the flanged face, plate at one end of each drill stem section and adapted to meet with the corresponding flanged face plate 38 at the opposite end of each drill stem section, as best shown,

in FIGURES 8 and 9.

Referring now to FIGURES 4 and 5, there is shown in greater detail, torque or torsion resisting means. A clevis bracket 40 is welded or otherwise secured to each of two adjacent posts 39 of the derrick structure 10. An angularly bent arm 41 has one end fitted between the clevis bracket jaws and pivotally held therein by means a distance equal to the length of a drill stem section, the drilling operation must be halted while a new section of drill stem is added. Conversely, as the drill mill is hoisted from the bore hole it must be raised intermittently to permit the drill stem to be shortened by removing each section of drill stem as it is removed from the bore hole. Since the hoist means must be disconnected from the drill stem as'new 'drill stern sections are added or drill stem sections are removed some means must be provided to hold the drill stem joint at a convenient work- 7 hole.

v for the bore hole.

The derrick platform 15 is desirably provided with a flanged ring 50, whose inside diameter [is equal to or slightly greater than the diameter of the hole being drilled, for the purpose of supporting temporary covering means In the illustrated embodiment, the bore hole is covered by means of a pair of semi-circular plates 51 supported in the flanged ring 50. Each of the plate members 51 is fitted. with an eye 52 adapted to be engaged by. cat-line. tackle or the like for removal of v the heavy plates. .Each'of plates 51 is provided with a V-no-tch 53 of a size and shape to permit passage of the drill stem 18 when the plates are in place in the derrick floor. bracket 55' by means of a bolt 56 and nut 57 is positioned with respect to the notch 53 that the free end of the dog overlies a portion of the notch. An eye 58 on the top surface .of the dog 54 enable the dog to beswung in its pivotal mounting out of alignment with the notch 53.

The wall of each drill stem section at the upper end adjacent the connecting joint between drill stem sections is A. dog 54 pivotally supported in a clevis-like provided witha cut-outportion or notch 59. A shoulder' 60 at the upper end of the cut-out portion or notch 59 in thedrill stem section engages the upper surfaces of the dog 54 when the dogs are in position for suspending the drill stem. When it is desired to lower the drill stem, the drill stem is lifted a shortdistance to free the dogs and the dogs 54 are swung out of the way away from'the path of the drill stem. Then when it is. desired to again engage the drill stem, the dogs are swung into thepath of the drill stem and the drill stem is raised or lowered until the free ends of the dogs 54 engage the notches 59 in the drill stem. When the drill stem: is being hoisted, it is not necessary that the dog be disengaged from the drill stem since the free ends of the dogs will simply ridge the edges of the drill stem until they engage the next following notch.

Drill Stem The details of construction of the drill stem are shown in FIGURES 8 and 9. In order for the drill stem to be held against rotation, it is preferably some shape other than circular in cross section. The square cross section shown is preferred but the drill stem might also be triangular, hexagonal, octagonal or some other shape if desired. The drill stem is composed of a plurality of sections each section being some convenient length, such as 10 feet, feet, feet, or the like. Each dnill stem section includes a pair of matching face plates 37 and 38 secured at opposite ends of a tubular casing 61. Casing 61 is preferably circular in cross section whereas the face plates are the desired non-circular shape of the overall drill stem cross section. The face plates are larger in area than the cross sectional area of casing 61 with the result that the edges of the face plate function as flanges to permit sections of drill stem to be secured together.

As shown in FIGURE 9, two drill stem sections are fastened together by bringing the matching flanged face plates together with a gasket 62 in between them and fastening together with heavy bolts 63 and 64 and nuts 65 for easy assembly and dis-assembly. The face plates are fastened at each of the corners to make a tight and rugged connection. Normally solid bolts are used but hollow bolts 64 may be used in some instances where it is desired to pass a further transmission line or tube through the drill stem, as explained in greater detail hereinafter.

An outer casing 66 of the desired non-circular cross section is supported from casing 61 by means of a plate 67 at each end of the drill stem section. The plate 67 is provided with a circular opening surrounding casing 61 and the plate is secured to the casing by welding or equivalent fastening means. The outer edge of plate 67 is welded or otherwise secured to the non-circular casing 66. The non-circulation casing 66 is of a length sufliciently less than the overall length of each drill stem section to provide working room for insertion and tightening of the fastening bolts.

The face plates 37 and 38 at opposite ends of the drill stem sections are of generally the same shape and size as the cross section of the non-circular casing 66 and are oriented so that no portion of the end plates extend out beyond the outer perimeter of the casing 66. This is to permit a cuttings carrier or other auxiliary equipment to be guided into and out of the bore hole along the drill stem without obstruction by the drill stem joints.

Positioned concentrically within the casing 61 are a plurality of pipes or tubes 68, 69 and 70 extending the entire length of the drill stem section from one face plate to the other. The pipes provide channels for the passage of drilling mud, water, steam, compressed air or other gas, bore hole cuttings and the like up or down through the drill stem, as necessary. The tubular members 61, 68, 69 and 70 are secured to the plates 37 and 38 at opposite ends of each of the drill stemsections. The tubular members may be screwed to the end flanges by providing the end of the tubes and channels in the end plates with threads of the same pitch so that an end plate may be screwed ontoall ot the tubes at once. The innermost and outermost tubes are accessible for welding. Alternatively, the inner tubular members may be seated in annular grooves milled in the inner faces of the drill stem section end plates and preferably gasketed to prevent leakage.

To alford'acc'ess to the channels between the tubular members of the drill stem sections to permit circulation of fluids through the drill stem, the flange plates 37 and 38 and the gasket 62 are each provided with a central circular opening 71 communicating directly with the innermost tubular member 70. A plurality of slots 72 disposed in an annular pattern spaced outwardly from the central opening communicates directly with the annular space between tubular members 70 and 69. A similar annular arrangement of slots 73 spaced outwardly from the slots 72 communicates through the flange plates and to close off one or more of the communicating channels through the drill stem this may be accomplished by use of gasketed blank plates omitting certain of the openings so as to seal off whichever channels are not desired to be used.

Still further communicating. means through the drill stem may be provided by the use of tubular members passing. through the drill stern between the outer noncircular casing 66 and the outer circular casing 61. A pipe or tube 75 may be passed through the space in the corners of the drill stem to circulate a fluid. such as compressed air or to pass an electric power line or the like. Tube 75 passes through plates 67 through water tight glands or similar packing. 76 and through the flange plates through a hollow bolt 64. The segments of tubing 75 in adjacent drill stem sections are joined together by means of a suitable water tight telescopic connector 77.

Instead of using concentric multiple pipes as illustrated and described, a plurality of parallel pipes of lesser diameter or a webbed conduit, as illustrated and described in my prior United States Patent 1,876,627, may optionally be employed. It is to be understood that in the event the construction of my earlier patent is used an outer noncircular casing would be provided to permit the drill stem to be held against rotation.

Cuttings Carrier A cuttings carrier for removal of bore hole cuttings is shown in FIGURES 10, 11 and 12. In FIGURES l3 and 14 the cuttings carrier structure is modified for use as a swab. In FIGURES 11 through 14 the cuttings carrier structure is shown in a large bore hole cased by casing 78. The cuttings carrier rests at the bottom of the bore hole on the top of a bumper 79 at the top of a drill mill indicated generally at 28. The cuttings carrier, indicated generally at 27, is essentially a large bucket adapted to be guided by the drill stem in its passage up and down through a bore hole. The carrier includes a heavy bottom wall or bulkhead 80 supported on a bottom spider member 81, both being provided with a central opening through which the drill stem 18 passes.

The bottom spider is supported by a plurality of heavy feet or pads 32 which perform several functions. The diameter of the cuttings carrier at the pads 82 is such as to just provide sliding clearance in the bore hole for the cuttings carrier. When the carrier is at the bottom of the bore hole resting on bumper 79 the bottoms of the pads 82 rest on the topof the drill mill housing and act as guides to keep the drill mill plumb. The spaces between the pads 82 provide passageways for cuttings from the drill mill to the carrier. As explained ingreater detail hereinafter, the pads also serve to elevate the carrier bottom wall so that the cuttings dump valve remains closed and the top edges of the pads serve as a landing bumper for a swabbing O-ring assembly.

The side wall 83 of the cuttings carrier is cylindrical and extends upwardly from the bottom bulkhead for a distance about equal to the diameter of the bore hole or greater. The carrier wall may be fluted if desired to facilitate the passage of larger cuttings. A top spider 84 is fitted into the top of the carrier to impart additional stability under the great weight and pressures to which the carrier is subjected when in use. A hoisting bail 85 extends up from the top spider to facilitate hoisting of the carrier from the bore holeby means of suitable hoisting 7 means on the surface.

The hoisting bail 85 is provided with a three-sided guide 86 to fit around the drill stem. The guide is desirably lined with sheets of hard rubber material 87 or the like to serve as a friction slide against the outer face of the drilli stem. A guide tube 88 extends between the top spider 84 and bottom spider 81 of the cuttings carrier aligned with guide 86. Guide tube 88 is also desirably lined with The weight of the valve itself and any material on top of it m the cuttings carrier holds the valve shut. When it. is desired to empty the cuttings carrier it is hoisted to the surface and positioned over a spout or flume or the like and lowered so that the bumper 94 is brought into contact with some projection and raised to unseat the valve element andpermit the contents of the carrier to be discharged.

A plurality of relief tubes 95 are provided extending from the top to the bottom of the cuttings carrier to facilitate lower of the carrier into a shaft or bore hole filled with liquid and raising the filled carrier through a liquid column. Because the bottom diameter of the carrier. is substantially the'same as the diameter of the bore holes considerable resistance is offered by liquids such as water or drilling mud against the passage of the carriersince the liquid can ordinarily be displaced only around the perimeter of the carrier. The provision of relief tubes 95 permits displacement of liquid also through the relief tubes and thereby facilitates passage of the carrier.

In some instances one of the relief tubes 95 may be used as a slide around apower line from a line spool or reel at the surface to a motor in the drill mill housing.

the drill mill at the bottom of thebore hole. The cut tings are carried up around the periphery of the bore hole byjthe drilling fluid, up around. the sides of the carrier, and settle into the carrier.

Because of its strongco-nst'ruction through the bottom bulkhead up to and including the hoisting hail, the carrier may be used as a drive hammer for driving standpipe, It may be filled with fluid or cuttings orlike materials for extra weight for use as a drive hammer or for supplying weight to the drill mill for drilling purposes, as, for example, in starting a hole at the surface. The carrier surrounding the drillstem may be suspended at some intermediate level between the drill mill and earths surface to keep the drill stern plumb and stiff. The carrier may be used as a safety platform or elevator to carry men into the bore hole. to condition the bore walls.

Two or more cuttings carriers may be used together for any of these purposes. When the carrier is provided with The space provided under the bottom of the carrier by" feet or pads 82 protects the line when the carrier lands on the bumper just above the drill mill housing atthe bottom of the bore hole.

When the cuttings carrier is used as a swab as shown in FIGURES 13 and 14 the use of the relief tubes is not desired and they are therefore closed off by means of 1 its tight fitting O-ring structure, it may be used as a swab to dewater the bore or to surge fluid and cuttings in the hole.

' 7 Drill Mills Two forms of drill mill structure which may be utilized in the large diameter drilling system of the present invention are shown in FIGURES 15 to 19. The drill mill shown in FIGURES 15 through 17 is illustrated as utilizing rolling. cutters of the type usually used in oil well drilling. The drill mill shown in FIGURES 18 and 19 is illustrated asutilizing diamond set saws. Other cutters may be used with either mill.

Referring particularly to FIGURES 15 through 17,'the drill mill indicated generally at '28 is connected to the bottom of the non-rotating'drill stem 18 by means of a flanged connector. Thedrill stem extension 99 which ex atends downthrough the drill mill housing is circular in cross sectionand is provided at its upper end with a -flanged face plate 38A having openings designed to regfister with the corresponding openings in the flange plate 37 at the bottom end of the lowermost drill stem section. The drill stemextension99 includes an outer casing 100 of circular cross section and a single inner tube 101 thus providing two channels :for circulation of fluid. Itwill he understood that additional channels for fliud may be provided as desired or needed as described in connection with the description of the drill stem in FIGURES 8 and 9.

The drill mill housing is generally in the form of a cylindrical tube open at one endand made up of a plurality of cylindrical sections as described hereafter. The

upper end of the housing includes a circular top plate screw caps 96 or plugs or equivalent closing means. 7 Alternatively, the relief tubes may be fitted withone-way check valves'which permit'flow of fluid through therelief tubesin one direction only. On other occasions pop-01f valves are fitted in the relief tubes which pass fluid only aftera predetermined pressure has been reached. Whenthe carrier is used as a swab, one or more flanged rings or annular-channels 97 each fitted with an O-Iing 93, of resilient material such as rubberor the like are secured to the outer perimeter of the cuttings carrier supported by the top surfaces of the feet or pads 82. If the carrier 102 having -a central openingthrough which the drill stem extension 99 passes. A bushing or sleeve of bearing maerial 103 is. disposed in that opening between the drill stem extension and the millhousing top plate to permit rotation of the mill housing about the drill stern extension. A deep annular flange 104 is provided on the top sun-face of the mill'housing top plate 102 surrounding the drill -stem extension and packing 105 is forced into the sidewall is flutedthe Q-ring supporting fitting must also In use,'the cuttings carrier is suspended from a hoisting v drum on the surface with wire rope tackle. The cuttings carrier can be operated at any level, as desired, in the derrick or up or down the bore hole, whether the drill stem and drill mill are in or out of the hole. It will be understood, ofcourse, that the function of the cuttings carrier" will vary depending upon the level of operation and whether the drill stem and drillmill are simultaneously in use. The cuttings carrier does not revolve and is not connected to anything that does revolve. I Its direction of movement is intended to be vertiealonly. The carrier is intended primarily for use to remove cuttings, from space'betweenthe 'flange and the drill stem extension to maintain a watertight seal at the top bfthedrill mill housing I V T 1 1 The uppennost-- 'section of the drill mill housing is. formed by acylindricalwall 106 welded. or similarly se- 7 cured to the periphery of' top plate 102 and having an inwardly extending lower annular flange 107. An intermediate circular plate 108 is bolted or" similarly secured to the bottom faceof flange 107.. Plate 108 is provided with a central opening throughawhich the .drill .shafit extension- 99 passes. A bushing 109 is provided in the opening between the plate 108 and the.drill stem exten- S1011 to permit the millhousing to be rotated about the drill stemextension.

Drillingthrustis applied to the drill mill housing by means of a heavy annular plate'110 secured to remain statronarywith the drill stem extension "and by means thrust bearing structures. The bearing structures include a pair of annular races 111 and 112 carried on opposite sides of the thrust plate 111), a cooperating annular race 113 supported under the housing top plate, a further cooperating annular race 114- carried by annular flange 107 and a plurality of ball or roller bearings 115 and 116. Since the drill stem is stationary, the thrust plate 116 is also stationary. However, when rotational movement is imparted to the drill mill housing by the motor power of the drilling elements, the housing is free to rotate about the drill stem extension.

The next following section of the mill housing serves as a motor housing and is made up of a cylindrical wall section 117 having an inwardly extending annular flange 118 at its upper end secured to intermediate plate 108 and an inwardly extending annular flange 119 at its lower end to which a second intermediate plate 120 is secured. Plate 120 is provided with a central opening through which the drill stem extension passes. A bushing 121 is positioned in the opening between the plate and drill stern extension. A tubular sleeve 122 extends between and is secured at opposite end-s to intermediate plates 108 and 12th and surrounds the drill stem extension to seal off the motor housing from the drill stern.

Motor means indicated generally at 123 are provided in the second section of the drill mill housing. A motor means is provided for each gang of cutters. The motor means may be electric motors, hydraulic motors such as mud driven turbines or the like, air motors, steam driven motors, diesel motors or the like, depending upon the particular needs and conditions. For stability, the drive shaft 124 of the motor means 123 preferably extends out both ends of the motor housing. The upper end of shaft 124 is journalled in bushing 125 in intermediate plate 168. The opposite end of the drive shaft is journalled in bushing 126 in the second intermediate plate 123. The lower end of drive shaft 124- is provided with a flange 127 for attachment to a matching flange 128 of a drive shaft extension 129. The flanged joint may be secured in any suitable manner.

A spur gear 130 is keyed to at least one of the drive shaft extensions 129. The teeth of gear 130 mesh with the teeth of a ring gear 131 surrounding and secured to the drill stem extension. Because the drill stem extension is held stationary, when shaft 124 and gear 139 are rotated by the motor means 123, the teeth of the rotating gear 139 mesh with the teeth of the stationary gear 131 and cause rotation of the entire drill mill housing. At the same time, the several gangs of cutters are rotated. The section of the mill housing in which this mill housing drive means is enclosed includes a third cylindrical wall section 132 provided with an annular inwardly extending flange 133 at its upper end secured to plate 12% and an annular inwardly extending flange 134 at its lower end to which a third intermediate plate 135 is secured. Plate 135 is provided with a central opening through which the drill stem extension passes. A bushing 136 between plate 135 and the drill stern extension permits rotation of the mill housing about the stationary drill stem. An annular spacer 137 is positioned between spur gear 130 and intermediate plate 135 to forestall the possibility of gear 138) slipping on the drive shaft.

The fourth segment of the drill mill housing includes a fourth cylindrical section of housing wall 133 having an inwardly extending annular flange 139 at its upper end by which the wall section is attached to the third interme diate plate 135 and an inwardly extending annular flange 149 at its lower end by which a fourth intermediate plate 141 is supported. An inside cylindrical wall section 142 provided with an upper outwardly extending flange 143 and a lower outwardly extending annular flange 144 is also provided between plates 135 and 141. Plate 141 is provided with a central opening through which the stationary drill shaft extension 99 extends. A bushing 145 in the space between the plate and drill stem permit rotation of the plate and the mill housing. The lower surface 111 of the fourth intermediate plate 141 is provided with an annular flange 146 surrounding the stationary drill stem extension. Packing material 147 is fitted into the space between the flange and drill stem to insure against leakage of fluid into the motor and drive gear housings.

The lower end of drive shaft extension 129 is journalled in bushing 148 in the third intermediate plate 135. The drive shaft extension is provided with a flange 149 by which it is secured to a matching flange 1500f a driven manifold 151 the upper end of which is journalled in bushing 152 in the fourth intermediate plate 141. The lower surface of plate 141 is provided with an annular flange 153 surrounding each of the manifolds 151. Packing material 154 is forced into the annular space between the flange and manifold.

The fifth drill mill housing section is enclosed within cylindrical wall section 155 which is provided with an upper inwardly extending annular flange 156 by which it is secured to the fourth intermediate plate and a lower inwardly extending annular flange 157 by which bottom plate 158 is supported. This section of the housing also includes an inner cylindrical wall section 159 extending between the plates 141 and 158 and having outwardly extending annular flanges 160 and 161 at the top and bottom, respectively.

It will be noted that the outer casing of the drill stem extension 99 terminates in this section of the housing and the channel between the outer casing and the inner tube 101 of the drill stem extension comniunicates directly with this section of the housing. A plurality of holes 162 are rovided in the inner wall 159 to permit flow of fluids from the outer drill stern channel to the opening 163 of the manifold 151.

The bottom plate 158 is provided with a central opening through which the inner tube 101 of the drill stem extension passes. A bushing 164 is fitted into the space between the bottom plate and inner tube to permit the bottom plate to be rotated about the inner tube. A deep annular flange 165 is provided on the upper surface of bottom plate 153 surrounding the drill stem inner tube and packing material is forced into the space between the flange and the inner tube. A similar flange and packing 167 and 168 are provided on the bottom surface of the bottom plate surrounding the inner tube. The lower end of manifold 151 is journalled in bushing 169 in bottom plate 158. Access openings may be provided in each of cylindrical mill housing wall sections as needed and desired. These openings are provided with gasketed cover plates which may be bolted or otherwise secured in place. The upper surface of bottom plate 158 is provided with a deep annular flange 170 surrounding each of the manifold tubes and the space between the flange and manifold is filled with packing material 1'71.

The lower end manifold 151 is provided with a flange 1'72 adapted to be secured to the flange 173 of a manifold extension tube 174 for carrying drilling fluid to the cutting surface and the cutting elements. An annular hearing race 175 is secured to the bottom surface of bottom plate 158 surrounding the manifold. A complementary bearing race 176 is secured to the manifold for rotation therewith and ball or roller bearings 177 rotate between the races. A housing 178 encloses the bearings and flanges 172 and 173. The manifold extension tube 174 is journalled in a bushing .179 in the bottom wall of housing 178. A deep flange 180 is provided extending from the bottom wall of the housing 178 surrounding the manifold extension tube. The space between the flange 180 and the tube is packed with packing material 181.

The gangs of cutter elements, indicated generally at 132 and 183, are secured to and rotate with the manifold extension tubes. The cutter gangs are housed in the last open ended section of the housing within a cylindrical bottom wall section 184 having an inwardly extending annular flange 185 by which the bottom wall section is secured to the bottom plate 158. The gang of larger cutters, indicated generally at 182, are supported from a cirelements.

cular heavy plate 186 having a central opening through which the manifold extension tube passes. The plate 186 is welded or otherwise secured to the manifold extension tube for rotation therewith. Each cutting member 187 is rotatably mounted at the lower end of a supportbracket or leg 188 which in turn is pivotally'secured to the heavy plate 186 by means of a bolt 189 and a nut 190 or equivalent pivotal fastening means. I

As best seen in FIGURE 16, when the motor means are the entire mill .housing rotates about the axis of the drill stem. When the drill mill is thus in operation the cutters 187 in their normal path of travel extend out beyond the periphery of the drill mill housing and into the space underlying casing shoe 192 at the bottom end of the bore hole casing 78.- This permits the bore hole to be cased progressively as the hole is'deepened. No problem arises so long as drilling proceeds satisfactorily. However, when it is desired to remove the drill mill from the cased bore hole, either at the completion of the drilling or to make some repair or adjustment or replacement of parts or the like, it is necessary that the extending cutter elements be retracted in order to permit the drill mill to be hoisted up through the cased hole.

As shown in FIGURE 17, this result is accomplished by reversing the directions of rotation of the motor means. When this is done the bumper blocks 191 no longer. bear against the pivoted brackets 188 and those brackets are permitted to swing inwardly to retract the cutting members 187 so that they lie wholly within the perimeter of v the drill mill housing.

The gang of smaller cutters, indicated generally at 183, is supported from a heavy circular plate 193 surrounding andsecured to another of the manifold extension tubes for rotation therewith. The gang includes a plurality of cutter members 194 supported for rotation about an angular axis. Each of the cutters 194 is supported from the end of a bracket 195 rigidly secured to the plate 193 as by means of bolts 196 and nuts 197 or equivalent fastening means. Because thegang of smaller cutting elements do not extend beyond the drill mill housing, they may be rigidly attached without the provision of means for retraction. The gangs of smaller cutters-.194 are rotated in the same manner .as the larger cutters. The individual cuttersrotate about their axes as the gangs rotate about the axes of the motor drive shafts'and the housing rotates about the axis of the drill stem. 1 In the rotation of the'several gangs of cutters it will be noted that'the entire surface area of the bottom of the hole is traversed by one or more of the individual cutting The mineral material through which the drill is passing is chipped and worn away byan infinite number of biting contacts with the teeth of the cutters. As a typical example, the drill mill for aneig'ht foot diameter shaft will weigh between about 15 and tons. This 'weight provides more than ample push to make the in- It will'be noted that the drill stem. same numerals gas used in connection with FIGURE 15.

12 drilling fluid passes through the manifold and manifold extension and is discharged in the area of the cutting elements 187 and 194 to lubricate the cutting members and to carry away the cuttings.

The drilling fluid and entrained cuttings are returned to the surface through the inner tube 101 where the cuttings are screened out and the-fluid is returned to the mud sump for recirculation. A further channel of the multiple pipe drill stern may be used to convey air under pressure to the vicinity of the lower end of tube 101 to give a jet assist for removal of cuttings. A screen or perforated cap is preferably applied over the open end of 'inner tube 101 to hold out any larger cuttings which might block the inner tube. The outside perimeter of the drill mill housing is desirably provided with one or more annular grooves into which O-rings 198 may be fitted to close off the space between the mill housing and the bore hole casing to create resistance to the drilling fluidto facilitate forcing it up through the center drill stem tube. 9

Where the cuttings carrier is used to remove cuttings as is usually desirable when working at depths exceeding 100 feet) O-rings 198- are not used and the drilling fluid and suspended cuttings are then forced up around the out side wall of the drill mill housing, between the housing and casing to the top of the drill mill housing, and then up along the outside wall of the cuttings carrier to the top of the carrier and'thence into the cuttings carrier. It will be understood that the bore hole will be filled with drilling fluid to a level above the top of the cuttings carrier but that the denser fluid containing suspended cuttings will settle in the cuttings carrier and the cuttings will tend to settle out of the fluid.

Under some circumstances both direct circulation (by which the cuttings are deposited in the cuttings carrier) and reverse circulation (by which the cuttings are forced up through the drill stem) maybe used together to attain a balanced circulation. Either means of transporting the cuttings to the surface may be used in the same bore hole at different levels depending upon depth and other conditions. One advantage of reverse circulation is that the fluid level in the bore hole need only be maintained just high enough to cover the drill mill. This is an advantage in that a much smaller volume of drilling fluid is needed. It'is a further advantage when drilling into a mine working as, for example, when drilling an escapeway. The weight of a fluidcolumn does not cause the roof to be broken in as the drill holes through and the mine is not flooded by a large column of fluid. I I

Referring now to FIGURES 18 and 19, there is shown a modified form of drill mill. The modified drill mill is indicated generally at 28A and includes a generally cylindrical housing mountedforrotation about the stationary Corresponding parts are identified by the With theexception of the thrust-bearing section of the housing,-the housing sections are enclosed in cylindrical wallsections having outwardly extending annular flanges for greater ease in assembly and disassembly of the housing. The housing sections are desirably joined by bolts and nuts. Thus, the motor housing is enclosed in a cylindrical wall section 117A.having an upper outwardly extending annular flange 118A and a lower outwardly extending flange 119A. Similarly the gear housing section is enclosed Within a cylindrical wall section 132A having outwardly extending flanges 133A and 134A. The drill fluid manifold section is likewise enclosed within a cylindrical wall section 155A having outwardly extending flanges 156A and 157A.. Access openings may be provided in the wall sections as previously described;

motor drive shaft and drive 'shaft extension are hollow to permit the passage of drilling fluid for lubrication of the thrust hearings in the uppermost housing section. The

' Specific means for powering an electric motor through 5 the drill'stem are shown. An electric cable 199 suitably insulated and waterproofed extends down through the annulus between the outercasingand inner tube of the stationary drill stem. The cable conductors 200 are passed through the casing wall while insulated from the I 13 Wall. to make electrical contact with conducting slip rings 201 of copper, bronze, carbon or the like secured in place around the drill stem casing. Brushes 202 or similar contact means supported by arms extending out from the motor housing make electrical contact with the rings 201 to power the motor means. Since drilling fluid may also be passed through the same annulus as the electrical cable it will be understood that the cable and the connections through the drill stem casing must be thoroughly waterproofed and insulated from the drilling fluid. It will also be understood that the conducting rings 2% must be electrically insulated from the drill stem.

The modified drill mill utilizes a pair of spur gears 13b meshing with ring gear 131 to rotate the mill housing. The manifold 151 is connected directly to the motor drive shaft 124 through the flange connection l27l5tl. The manifold extension tube 174A which serves as a drive shaft for the diamond saw drilling elements is somewhat elongated. A housing 178A encloses the bearing structure 175477 and the flanged connection 172473. For lubrication of the bearings and the bushing on which the gang housing rotate about the manifold tube extension a plugged opening 293 is preferably provided for introduction of lubricant.

The gangs of diamond saws are enclosed in smaller rotating housings indicated generally at 204. The upper portion 285 of the gang housing is generally in the shape of a cylindrical bell having an upstanding cylindrical collar portion 206 which is internally threaded. The upper portion 205 of the gang housing serves as a gear housing for rotation of the individual cutting elements and the gang housing. The gang housing is supported on an annular shoulder 207 at the lower end of a tubular shaft extension 208 of the housing 178A. A bushing 269 is positioned in the space between the collar portion 2% and the tubular shaft extension to permit rotation of the gang housing around the tubular shaft. The space between the threaded collar 2% and the tubular shaft extension 2&8 s filled with packing material 21% held in place with a ring nut 211.

The manifold tube extension 174A extends through the tubular shaft extension 268 and is journalled therein in a bushing 23.2. The tubular shaft 298 carries a plate 213 at its lower extremity. Plate 213 carries a plurality of short vertical shafts 214 journalled in bushings 215. A pinion gear 216 is keyed to each of the shafts 2.14 above plate 213. The teeth of the pinion gears 216 mesh with the teeth of a ring gear 217 secured to or formed integrally with the inside of the gear housing body 295. A further pinion gear 218 is keyed to the lower end of each of the shafts 214 on the bottom side of plate 213. The teeth of pinions 218 mesh with the teeth of a further pinion 219 which is keyed to the manifold tube extension 174A which is driven from the motor drive shaft. Thus when tubular Shaft 174A rotates pinion 219 rotates with it. Pinion 219 meshing with pinions 218 rotate shafts 214 and pinions 216 at the opposite end of the shafts. Pinions 216 in turn meshing with the teeth of ring gear 217 cause the entire gang housing 294 to rotate.

The gang housing includes an intermediate portion having a circular plate 223 secured to and forming the bottom Wall of the gear housing 2% and having 9. depending cylindrical wall portion 221. A bottom plate 222 is secured to the depending edge of cylindrical wall 221. A cylindrical skirt 223 depending from the bottom plate completes the exterior housing structure. The diamond set saws extend beyond the skirt 223 as hereinafter described. The intermediate plate 226 surrounds the tubular manifold extension 174A and is journalled for rotation round-it by means of bearing structure 225 and bushing 226. Bottom plate 222 also surrounds the manifold extension 174A and rotates around it by virtue of bushing 227. An annular flange 228 extends from the bottom surface of the bottom plate 222 surrounding the manifold extension 174A. The space between the flange and the tubular member is filled with packing material 229 held in place by means of a ring nut 230.

The diamond cutters 224 are each secured at the end of a shaft 231. Shafts 231 are vertically disposed and extend through plates 220 and 222 journalled in bushings 232 and 233 and ball bearing structures 234. The upper ends of the shafts 231, where they pass through plates 22% are of reduced diameter. The thrust of the gang housing is applied to the diamond cutters through the ball bearing 234. The bottom surface of bottom plate 222 is provided with an annular flange 235 surrounding each of the shafts 231. The space between the flange and shaft is filled with packing material 236 held in place byring nuts 237.

A small pinion gear 238 is keyed to the upper end of each of shafts 231. The teeth of pinions 238 mesh with the teeth of a spur gear 239 keyed to rotate with the tubular manifold extension 174A which is an extension of the motor drive shaft. Thus, as the motor drive shaft turns, gear 239 is rotated and in turn gears 238 are rotated to rotate the diamond cutters 224. At the same time that the individual diamond cutters are being rotated the gang housing is being rotated as heretofore described. The rotating diamond cutters revolve about the axis of the motor drive shaft and at the same time the overall drill mill housing is rotated about the axis of the drill stem as heretofore described. Thus, in the course of rotation of the individual cutter elements 224 and their revolution about the axis of the gang housings 204 and the revolution of the gang housing about the axis of the main drill mill housing all portions of the surface of the bottom of the bore hole are acted upon by the cutter elements which bite into and chip away the mineral material through which the bore hole is drilled.

Drilling tluid is directed down through the drill stem to the space between plates and 158 and thence through the manifold to the drilling area in much the same manner as described in connection with FIGURE 15. The cuttings can be returned to the surface either by reverse flow back up through the inner tube 101 or collected in a cuttings carrier and hoisted to the surface. Because the housing of the drill mill utilizing the diamond cutters does not closely hug the bore hole relatively little resistance is offered for reverse circulation of the drilling fluid through the drill stern. This can be remedied however, by positioning a cuttings carrier equipped with D-rings for use as a swab on the bumper 7 above the drill mill housing. In this manner the flow of drilling fluid and cuttings through the annulus surrounding the drill mill housing is resisted and circulation is up through the drill stem instead.

The diamond cutters 224 of this modified form of drill mill may be replaced by other cutting elements such as small clusters of oil well type rock cutters and the like. The two larger gang cutters shown may be complemented by the use of a pair of smaller gang cutters of substantially the same construction positioned in the space within the bore hole adjacent to the larger gangs substantially as shown in the plan view of the first embodiment of the drill mill. In order to balance torsion of the drill stern one gang of cutters is desirably rotated in one direction and its complementary gang is then rotated in the opposite direction. This is true for either the embodiment of FIGURE 15 or that of FIGURE 18. In addition to balancing torsion of the drill stem the oppositely rotating drill ganges also help to keep the stem and the drill mill plumb.

For some purposes such as, for example, in starting a bore hole through rock the rotary cutting elements of the drill mills may be replaced by relatively soft rotary plates. Hard shot is introduced to the drill mill and drilling is accomplished by the action of the rotary plates moving the hard shot under pressure against the face of the rock.

The shot may be introduced to the drill mill through one of the channels of the drill stem.

In some instances it may be desired to cut a core as the drilling proceeds. This may be done with the apparatus of the present invention by utilizing somewhat smaller gangs of rotary cutting elements. The diameters of the areas swept by the rotating gangs must be such that the cutter paths are spaced apart at the center of the bore hole. This center portion of the bore hole will not be swept by the rotating and revolving cutter elements with'the result that the cutters will describe an annular cut. The uncut core will be at the center of the bore hole. Depending upon thediameter of the core it may beretrieved through the central channel of the drill stem'or sible core permitted by the mill housing construction'the drill mill may be removed from the bore hole to permit 'after the drill mill has progressed to cut the deepest pos- I and the like the large diameter bore hole drilling system without departing from thespirit and scope thereof. The specific embodiments described are given by way of example only and the invention is limited only by the terms of the appended claims. I

I claim:

1. An apparatus for the drilling of large diameter vertical bore holes in the surface of the earth which com prises a large diameter drill mill adapted to work at the bottom of a vertical bore hole, a stationary vertical drill stem extending from said drill mill to the earths surface, said drill stem being non-circular in cross-section and comprised of a plurality of elongated sections each including multiple pipes, said drill mill including ahousing, a central vertical tubular shaft extending from the upper end of said housing and adapted to be rigidly connected to said drill stern, said housing journalled on said tubular shaft for rotation relative thereto, a plurality of rotary gangs of cutting members extending from the bottom of said drill mill housing, each of said gangs including a plurality of individual rotary cutting members, motor means within said housing operatively connected to rotate each of said gangs of cutting members, said motor means secured within said housing for movement therewith and operatively connected to said-central tubular shaft to rotate said housing with respect to the tationary drill stem. i

2. Apparatus according to claim 1 further characterized in that said drill stem sections'include' at their oppositeends matched flangedend plates of area andcross section corresponding to thenon-circular cross section of the drill stem, said end plates being adapted for connection'of adjacent drill stem section-s and provided with openings communicating with said multiple pipes.

3.Ap-paratus according to claim 1 further character- 7 ized in that said non-circular cross section is square and.

said multiple pipes are concentric. I

4. Apparatus according to claim 1 further characterized in that derrick means are provided at the surface of the earth and means are supported by said derrick for holding said drill stem against torque.

5. Apparatus according to claim 4 further characterized that said torque resisting means includes a pair of pivotally swingable arms supported from adjacent posts of said derrick, the free ends of said arms 'being' fitted with jaw members adapted to engage said drill stem and means for securing said jaw members together.

6. Appartaus according to claim 4 further characterized in that said derrick means includes a derrick floor adapted to overlie the bore hole to be drilled, an opening in said floor at least as great in diameter as said bore hole, a two-part cover for said opening, a central smaller 7 15 7 opening in said cover for passage of said drill stem, a

pair of dogs each pivotally supported at one end by one 7 of said cover segments adjacent said central opening, the free ends of said dogs adapted to be swung on said pivotal supports over said central smaller opening into the path of said drill stem.

7. Apparatus according to claim 6 further characterized in that said drill stem is comprised of a plurality of elongated sections of non-circular cross section each provided with a pair of cut-out portions diametrically opposed, spaced equidistant from one end of the drill stern section and adapted to be engaged by said dogs on the derrick to support said drill stern in the bore hole.

8. Apparatus according to claim 1 further characterized in that means are provided for conveying cuttings from said drill mill to the surface, said means comprising a cylindrical cuttings carrier adapted to be suspended in the bore hole above the drill mill and around said drill stem.

9. Apparatus according to claim 8 further characterized in that said cuttings carrier is'provided with a circular bottom wall and cylindrical side, Wall, a central guide tube adapted to pass said drill stem extending from the top of said side wall through said bottom wall, a strengthening spider extending from said guide tube to said side wall and a plurality of open relief tubes extending through said bottom wall to the top of said side wall.

10. Apparatus according to claim 9 further characterized in that said cuttings carrier is provided with at least one dart valve in said bottom wall, a plurality of at least three spaced apart arcuate feet at said bottom wall, said arcuate feet extending downwardly below said bottom wall to define a space thereunder and outwardly beyond the periphery of the cylindrical side wall to form a plurality of lands around the outside. of said carrier.

11. Apparatus according to claim 10 further characterized by the provision of at least one annular outwardly facing channel surrounding the cylindrical wall of said cuttings carrier and seated on the lands formed by the tops of said annular feet, and an annular ring of reilient material in said channel.

12. Apparatus according to claim 1 further characterized in that said drill stern and drill mill central tubular shaft rigidly secured thereto are multichanneled, adapted for the transmission of at least two different fluids therethrough; said drill mill housing is multichambered, one of said chambers communicating with one of the channels of said central tubular shaft'and another of said chambers communicating with another of said channels; said motor means including a tubular drive shaft extending into said drill housing chambers, openings in said tubular drive shaft within said chambers,

"whereby said drive shaft is in communication with said channels of the central tubular shaft for transmission of fluid from one of said channels through the drive shaft fluid introduced to vsaid drill mill may be conducted to lubricate said cutting members and be separately returned to the surface with cuttings.

14. An apparatus for the drilling of large diameter vertical bore holesin the' surface of the earth which comprises a large diameter drill mill adapted to work at the bottom of a vertical bore hole, a stationary ven 'tical drill stem extending from said drill mill to the earths surface, said drill mill including a housing, a central vertical tubular shaft extending from the end of said housing and adapted to be rigidly connected to said drill stem, said housing journalled on said tubular shaft 17 for rotation relative thereto, a plurality of rotary gangs of cutting members extending from the bottom of said drill mill housing, each of said gangs including a plurality of individual rotary cutting members, motor means within said housing operatively connected to rotate each of said gangs of cutting members, said motor means secured within said housing for movement therewith and operatively connected to said central tubular shaft to ro tate said housing with respect to the stationary drill stern, said motor means including a plurality of motors arrayed in said housing about said central tubular shaft, the drive shafts of said motors being elongated, vertical, parallel to said tubular shaft and journalled for rtation in said housing, a separate smaller housing for each gang of cutting members, each of the gang housings being journalled for rotation about one of said motor drive shafts, gear means fixed to said drive shafts and operatively connected to gear means fixed to said gang housing for rotation of said gang housings about said drive shafts, a plurality of rotary cutting members supported from vertical shaft means arrayed about said motor drive shafts Within each of said gang housings and journalled for independent rotation with respect to said gang housings, gear means fixed to said motor drive shafts operatively connected to gear means fixed to said vertical shaft means for independent rotation of the cutting members.

15. A large diameter drill mill for drilling large diameter vertical bore holes in the surface of the earth and adapted to work at the bottom of a vertical bore hole, said drill mill including a housing, a central vertical tubular shaft extending from the upper end of said housing and adapted to be rigidly secured above said housing, said housing being rotatably mounted on said central tubular shaft, a plurality of rotary gangs of cutting members extending from the bottom of said drill mill housing, each of said gangs including a plurality of individual rotary cutting members, motor means within said housing operatively connected to rotate each of said gangs of cutting members, said motor means being operatively connected to said central tubular shaft to rotate said housing with respect to said shaft, said drill mill central tubular shaft being multichanneled and adapted for transmission of at least two different fluids therethrough, said drill mill housing being multichambered, one of said chambers communicating with one of the channels of said central tubular shaft and another of said chambers communicating with another of said channels, said motor means including a tubular drive shaft extending into said drill housing chambers, openings in said tubular drive shaft within said chambers, whereby said drive shaft is in communication with said channels of the central tubular shaft for transmission of fluid from one of said channels through the drive shaft to another of said channels.

16. A drill mill according to claim 15 further characterized in that one of said drill housing chambers in communication with a channel of the central tubular shaft of the drill mill housing and with said tubular motor drive shaft is the lowermost chamber of the housing, said chamber is open at the bottom and contains the rotary gangs of rotary cutting members, whereby drilling fluid introduced to said drill mill may be con- 18 ducted to lubricate said cutting members and be separately returned from the drill mill with cuttings.

17. A large diameter drill mill for drilling large diameter vertical bore holes in the surface of the earth and adapted to Work at the bottom of a vertical bore hole, said drill mill including a housing, a central vertical tubular shaft extending from the upper end of said housing and adapted to be rigidly secured above said housing, said housing being rotatably mounted on said central tubular shaft, a plurality of rotary gangs of cutting members extending from the bottom of said drill mill housing, each of said gangs including a plurality of individual rotary cutting members, motor means within said housing operatively connected to rotate each of said gangs of cutting members, said motor means being operatively connected to said central tubular shaft to rotate said housing with respect to said shaft, said motor means including a plurality of motors arrayed in said housing about said central tubular shaft, the drive shafts of said motors being elongated, vertical, parallel to said central tubular shaft and journalled for rotation in said housing, a separate smaller housing for each gang of cutting members, each of the gang housings being journalled for rotation about one of said motor drive shafts, gear means fixed to said drive shafts and operatively connected to gear means fixed to said gang housings for rotation of said gang housings about said drive shafts, a plurality of rotary cutting members supported from vertical shaft means arrayed about said motor drive shafts within each of said gang housings and journalled for independent rotation with respect to said gang housings, gear means fixed to said motor drive shafts and operatively connected to gear means fixed to said vertical shaft means for independent rotation of the cutting members.

References Cited by the Examiner UNITED STATES PATENTS 724,675 4/03 Decker 285-133 1,292,159 1/19 Trumpour 61-85 1,523,604 1/25 Miller 166-168 1,666,461 4/28 Lord -95 1,866,082 7/32 Carlson 175-292 1,999,115 4/35 Shinn 175-95 2,016,068 10/35 Bannister 175-96 2,054,859 9/36 Kitching 285-133 2,105,091 1/38 MacKay 175-95 2,184,065 12/39 Zublin 175-96 2,215,710 9/40 Miller 166-168 2,466,709 4/49 Karr 262-15 2,594,884 4/52 Dornacher 166-168 2,595,126 4/52 Causey 175-96 2,850,264 9/58 Grable 285-133 2,942,850 6/60 Heath 175-106 FOREIGN PATENTS 17,985 5/04 Austria. 197,7 67 5 5 8 Austria.

CHARLES E. OCONNELL, Primary Examiner.

BENJAMIN BENDETI, BENJAMIN HERSH,

Examiners. 

1. AN APPARATUS FOR THE DRILLING OF LARGE DIAMETER VERTICAL BORE HOLES IN THE SURFACE OF THE EARTH WHICH COMPRISES A LARGE DIAMETER DRILL MILL ADAPTED TO WORK AT THE BOTTOM OF A VERTICAL BORE HOLE, A STATIONARY VERTICAL DRILL STEM EXTENDING FROM SAID DRILL MILL TO THE EARTH''S SURFACE, SAID DRILL STEM BEING NON-CIRCULAR IN CROSS-SECTION AND COMPRISED OF A PLURALITY OF ELONGATED SECTIONS EACH INCLUDING MULTIPLE PIPES, SAID DRILL MILL INCLUDING A HOUSING, A CENTRAL VERTICAL TUBULAR SHAFT EXTENDING FROM THE UPPER END OF SAID HOUSING AND ADAPTED TO BE RIGIDLY CONNECTED TO SAID DRILL STEM, SAID HOUSING JOURNALLED ON SAID TUBULAR SHAFT FOR ROTATION RELATIVE THERETO, A PLURALITY OF ROTARY GANGS OF CUTTING MEMBERS EXTENDING FROM THE BOTTOM OF SAID DRILL MILL HOUSING, EACH OF SAID GANGS INCLUDING A PLURALITY OF INDIVIDUAL ROTARY CUTTING MEMBERS, 